Dye-doped cholesteric liquid crystals are used to design wide range frequency tunable distributed feedback lasers. Two novel methods to control the periodicity of a cholesteric structure are used to obtain the tuning of these lasers. The first method is based on the photo-transformation of cholesteric molecules that induces a shift of the selective reflection band with an all-optical control of the lasing wavelength. The second method employs the standard technique to modify the cholesteric helical pitch by means of a chiral dopant, but with an original architecture of the device: cells are now characterized by a gradient of chiral dopant concentration and by spatial distribution of different dyes, obtaining a position sensitive, continuous wavelength fine tuning of laser emission in a range of about 300 nm. Lasing on the defect mod is also investigated.
Two strategies for tunable cholesteric lasers
BARBERI, Riccardo Cristoforo;
2010-01-01
Abstract
Dye-doped cholesteric liquid crystals are used to design wide range frequency tunable distributed feedback lasers. Two novel methods to control the periodicity of a cholesteric structure are used to obtain the tuning of these lasers. The first method is based on the photo-transformation of cholesteric molecules that induces a shift of the selective reflection band with an all-optical control of the lasing wavelength. The second method employs the standard technique to modify the cholesteric helical pitch by means of a chiral dopant, but with an original architecture of the device: cells are now characterized by a gradient of chiral dopant concentration and by spatial distribution of different dyes, obtaining a position sensitive, continuous wavelength fine tuning of laser emission in a range of about 300 nm. Lasing on the defect mod is also investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
